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Assembly of the Galactic Halo System Based on Carbon-Enhanced Metal-Poor Stars

Published online by Cambridge University Press:  02 August 2018

Young Sun Lee
Affiliation:
Department of Astronomy & Space Science, Chungnam National University, Daejeon 34134, South Korea email: [email protected]
Timothy C. Beers
Affiliation:
Department of Physics & JINA-CEE, University of Notre Dame, Notre Dame, IN 46556, USA
Jinmi Yoon
Affiliation:
Department of Physics & JINA-CEE, University of Notre Dame, Notre Dame, IN 46556, USA
Young Kwang Kim
Affiliation:
Department of Astronomy & Space Science, Chungnam National University, Daejeon 34134, South Korea email: [email protected]
Jaehun Jeong
Affiliation:
Department of Astronomy & Space Science, Chungnam National University, Daejeon 34134, South Korea email: [email protected]
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Abstract

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There is growing evidence that, among the various subclasses of carbon-enhanced metal-poor (CEMP) stars, the outer halo of the Milky Way exhibits a higher frequency of CEMP-no stars (those having no over-abundances of heavy neutron-capture elements) compared with the CEMP-s stars (those with over-enhancements of the s-process elements), while the inner halo shows a higher frequency of CEMP-s stars. We map out fractions of CEMP-no and CEMP-s stars in the inner- and outer-halo populations, separated by their spatial distribution of carbonicity ([C/Fe]), a so-called “carbonicity map”, based on a sample of over 100,000 main-sequence turnoff stars with available spectroscopy from the Sloan Digital Sky Survey. The CEMP-no and CEMP-s objects are classified by different levels of absolute carbon abundances for our sample, A(C). We also present kinematic and orbital characteristics of these subclasses for each population. The contrast appearing in these characteristics provides critical constraints on the assembly history of the two primary stellar components of the Galactic halo.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2018 

References

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